Refractory arch furnace roof



May 18, 1965 I 4 R. P. Ross 3',1`83,865

REFRACTORY ARCH FURNACE ROOF Filed March 8, 1962 2 Sheets-Sheet 1INVENTOR. /Foafkr /oas aw-QL 8%, 14

TTORIVEY May 18, 1965 R. P. Ross REFRACTORY ARCH FURNACE ROOF 2Sheets-Sheet 2 Filed March 8, 1962 INVENTOR. 63 Roaer 1? Koss rraR/vzrUnited States Patent O aisases REFRACTORY ARCH FURNACE R001? Robert P.Ross, Louisville, Ky., assignor to Corhart Refractories Company, Inc.,Louisviile, Ky., a corporation of Delaware Filed Mar. 8, 1962, Ser. No.173,298 S Claims. (Cl. 110-99) This invention relates to an improvedstable refractory arch or roof for reverberatory furnaces, particularlyopen hearth steelmaking furnaces.

In the past, silica brick was most commonly used in the construction ofsprung roofs on open hearth furnaces. One very desirable characteristicof a silica roof is that very little thermal expansion occurs above1200o F. Thus, normal temperature changes during each heat and duringcooling periods for repairs to various parts of the furnace caused verylittle movement in the roof and its Contour remained fairly stable forthe entire life of the silica refractory.

For more than a decade, more and more quantities of basic refractorybrick have been used instead of silica brick because of the ability ofthe basic refractory to withstand higher temperatures than silicarefractory. Silica briclc is not capable of withstanding temperaturesmuch in excess of about 3000 F. and care had to be taken to avoidoverheating the roof. Moreover, with the advent of tonnage use of oxygenin the open hearth, silica brick could no longer be used because of thehigher temperatures generated, in many cases exceeding 3300 F.

However, roofs of basic refractory are burdened with the dynamic effectscaused by the characteristic thermal expansion of the material, which isnearly linear frorn room temperature to Well above the furnacetemperatnres in the present-day tonnage oxygen practice. It has beenfound that simple sprung arches of basic refractory will not uniformlyrise upon heatng nor uniformly settle down upon Cooling. They will sagvery 'severely in certain areas and hump up excessively in adjacentareas. Moreover, the humps and sags occur unpredictably in manydifferent areas in different roofs. In those areas where the refractoryhumps, the bricks are severely pinched together near the hottest facecausing crumblng and spalling of the brick. Sagging areas tend to openthe joints between individual bricks in a row at the hot face allowingany thermally spalled portions of the bricks to drop out, which portionswould otherwise be held in place by proper contact with adjacent bricksUltimately roof failure occurs in the collapse of a portion of the roofmuch too large to be patched and long before the refractory would haveotherwise been deteriorated by hot corrosive environment and thermalcycling conditions, such as is found in the open hearth.

When one or more rows of brick lose their Contour, an imbalance inlateral thrust forces is generated along the rows. This results from thefact that the sagged portions form a low, or flat, arch and the humpedportions form a high arch. It |is a demonstrable fact that low archeshave a much greater lateral thrust along the rows than high arches. Thusthe higher thrust forces of the -sagged portion of the rows causefurther humping distortion and as the humping increases, it allows thesagged portions to further sag with a resultant increase of lateralthrust forces in the latter area. Hence, this shifting process isaccelerated as shifting progresses until ultimate failure or collapseoccurs. This shifting is fundamentally caused by the dynamic nature of arefractory, when used in an arched roof of a furnace having varyinginternal temperatures, that has a substantially linear positivecoelficient of thermal expansion over the range of temperatures to whichit is subjected.

ice

Originally the basic refractory bricks were made simply by compactingand sintering granular material, such as magnesite or mixtures ofmagnesite and chrome ore, with or without additional constituents toeflect improved chemical bonding upon sintering. These bricks haverelatively low strength and are not able to withstand any substantialdegree of pinching loads caused by humping and sagging.

Some improvement in roof life was attained by encasing the chemicallybonded brick, which acted to provide greater strength to the inherentlylow strength sintered material. Further improvement was attained byadditionally embedding a metal plate within the refractory block. Thecasing and internal plates not only increase the strength, but they tendto hold spalled segments of the brick together. However, thesetechniques do not control the humping and sagging movements, but rnerelyresist higher pinching loads before the brick are forced out of properposition to such a degree that the roof coliapses at that point.

The erratic humping and sagging behavior of these basic roofs lead tothe Widespread opinion that it was necessary to suspend as many of theindividual bricks as possible. However, this does not prevent humpingand requires more expensive bricks adapted for Suspension.

ln recent years, reasonably successful Contour control systems have beendeveloped for chemically bonded basic brick that greatly increase rooflife, for example, from about heats to 300 or more heats in open hearthfurnaces not using tonnage Oxygen. The systems bascally comprise acombination of hold-down and hold-up effects. The hold-down effectamounts to rigidly blocking down of a new cold roof by means of aplurality of jacks or steel beams attached to the furnace overheadstructure or binding. These jaclcs or beams rigidly hold a series ofspaced-apart transversely-extending beams against the top of thelongitudinally-extendng, arcuate rows of brick comprising the roof. Thehold-up effect is attained by vertically disposed,longitudinally-extendng, steel plates placed between adjacent arcuaterows of brick, which plates extend from the hot face of the roof to wellabove the cold face. These plates are rigidly suspended either from theoverhead binding or from interconnection with the transversely-extendingbeams. The net effect of the above described systems is to hold andstably maintain the original roof contour.

At least two major factors appear to contribute to the success of thesesystems. The first is the capability of these chemically bondedrefractory roofs to be rigidly blocked down and absorb the thermalexpansion effects without any Contour distortion occurring between thepoints of hold-down. The second is the high degree of bonding betweenthe vertically-extending plates and the adjacent arcuate rows of briclr.

The first factor .seems to be attributable, at least in part, to therelatively low hot strength of the refractory, or more significantly tothe corresponding ability of the refractory to be plastically deformedat furnace temperatures.

The second factor seems to be attributable mainly to ability of theplates and bricks to fuse together, although frictional or mechanicalbonding may also contribute to the bonding.V Where a portion of thebrick rows are not adjacent to vertically-disposed plates, these latterrows bond equally well to those brick rows which are adjacent theplates. Hence, all the rows of brick are hold up and have their contourControlled, directly or indirectly, by these plates.

During the past decade, a new ytype of basic brick for furnace archeshas been proposed and has been utilized in open hearth furnace roofs.This basic 'refractory is commonly referred to as fused cast orheat-cast byl ata-8,8%

virtue of the fact that the -refractory oxide materials used to make thebrick are melted and then cast into preformed molds to solidify intoappropria'te shapes. Exemplary of this type of basic refr-actory arethose disclosed in U.S. Pa-tents 2599566 and 2,690,974 to R. l. Magri,Jr.

This fused cast type of basic refractory is ideally suited for furnaceroofs, such as in open hearth furnaces, since it has an inherentlysuperior resistance to deterioration caused by hot -ferruginous slagsand slag vapors as cont'rasted With chemically bonded basic refractory.Moreover, the fused cast refractory possesses a much higher hotst'rength than the chemically bonded vrefractory. However, like thechemically bonded basic brick, the fused cast basic brick possessessentially the same thermal expansion characteristics and sutfer thesame detrirnent of hum-ping and sagging in a simple sprung arch roof.

In attempts to improve roof life and control 'the contour of fused castbasic .reflractory roofs, |the aforementioned contour control systems,that 'were successful for chemically bonded brick, Were adapted for useWith the fused cast basic brick. Unfortunately, these atternpts were farfrom successful, averaging at best only 200-250 heats before collapse ofthe roof in open hearth furnaces not using tonnage oxygen.

The lack of success with 'the prior art systems in constructing fusedcast basic refractory arches is due to three important characteristicspeculiar to this 'refractory. One of these is that .the refractory isnot plastic at ordinary open hearth furnace temperatures, by virtue ofits much higher hot strength. The second important characte'ristic isthe relatively wide Variation in dimensions of the brick, as contrastedWith chemically bonded brick. This Variation in dirnension inheres fromthe manufacturing process wherein a billet of refractory is cast andthen sawed into brick of required size and shape. The resulting cast andsawed dimensions cannot be economically held as uniform for every brickas can be done for the less costly chemically bonded brick. The thirdcharacteristic is that only very limited chemical bonding or fusing-reaction takes place between oxidized steel plates and the fused castrefractory.

As a result of the lower plasticity and higher strength of the fusedcast brick, a rigidly held down roof of this brick is unable to absorbthe thermal expansion effects without hazard of damages to the furnacestructure. The tremendous humping forces, caused by high hot loadstrength and loss of contour, bent the transVersely-extending beamsupwa-rd in some cases and caused the roof to rupture out upwardlybetween the beams in other cases.

The dimensional Variation characteristic of the fused cast brick and thecharacteristic limited reaction between iron oXide and fused cast:refractory apparently cause the almost complete lack of bonding to thevertically-disposed plates that was found to exist. Hence, these platesexerted no contour control. When the humping occurred in one portion ofan arcuate brick row, another portion of that row Was allowed to sag.Moreover, the plates were found in most instances to be burned out towithin 1" of 'the cold face of the roof in Contrast to chemically bondedbrick arches where the usual burn-out of the plate is not much more than1" to 2 from the hot face.

It Was notable in all the fused cast refractory roofs utilizing theprior art systems that the remaining portions of the roof, whichmaintained their contour, still had from 56% to 90% of the originalthickness or usable life left, it being understood that usable life willextend to a minimum thickness not substantially smaller than 2 inches.

It has now been discovered that the foregoing problems associated withfused cast refractory roofs can be 'overcome by a unique roofconstruction that provides means to rnaintain substantially the originalarch contour, without humping and sagging, throughout substantially thefull useful life of the 'refractory This construction provides for adual effect found essential for success,-

ful contour control of fused cast refractory roofs. A combination meansprovides a hold-up and hold-down on the refractory 'roof whilesimultaneously allowing a limited amount of upward and downward movementof the arched brick rows. The net eifect'is that the original smoothcontour of the -arch is continuously maintained while simultaneouslyallowing the thermal expansion effects of the fused cast refractory tobe absorbed by rise and fall of the brick -rows With changes intemperature. It should be understood here that what is mearit by upwardmovement of the brick rows and by rise of the brick rows," in thisspecification .and the appended claims, is that the lateral expansion ofthe brick occurring When the brick is heated causes an increase in a'rclength of the arch and, since the brick rows have their ends rigidlypositioned at fixed points, i.e. fixed skewbacks, the brick nearest thecrown of 'the arch will rise the most with the amount of :rise beingsubstantially uniformly lesser and lesser for each brick further awayfrom the crown down to the point where there is substantially no rise inthe brick adjacent the fiXed skew- -backs Likewise, the meaning ofdownward movement of the brick rows and of fall of the brick rows is thesame as the above, but in the reverse direction or sense. Hence, eachbrick does not rise and fall the same distance as every other brick.Although there will be some change in the radius of curvature in thearch with this rise and fall of the brick rows, the original smoothcontour of the arch is vsubstantially the same at all times during theuseful life of the roof.

The limits of upward and downward movement of the brick rows are the'points where rigid hold-down and hold-up, respectively, are effected.For continuously effective contour control in this arrangement, thelimited movement allowance is required to be substantially equal to therise and fall of said brick rows, while having their original smootharch contour substantially maintained, resulting solely from thermalexpansion and contraction of the brick caused by changes in furnaceOperating temperatures. Thus, for any particular' furnace process, theallowance can be determined from the known Operating temperature rangefor the process, the known coeicient -of thermal expansion for theparticular refractory used and the span or arch length of the roof.

lt is thus a principal object of this invention to provide a fusecl castrefractory arched furnaced roof construction having means to control andmaintain the smooth contour of the arch during furnace Operations forsubstantially the full usable life of the refractory, whereby Sectionsthat tend to sag ar held up and Sections that tend to hump are helddown.

ft is another object of this invention to provide a refractory archedfurnace roof construction having means to allow a limited amount ofupward and downward movement of the arched brick rows, while maintainingsubstantially their original smooth arch contour, substantially equal tothe rise and fall of said brick rows resulting solely from thermalexpansion and contraction of said brick caused by changes in theirtemperature.

Additional objects, features and advantages of the present inventionwill become apparent, to those skilled in the art, from the followingdetailed description and the attached drawings, in which, by way ofexample, preferred embodiments of this invention are illustrated.

In the drawings, FGURE 1 is a sectional, elevation view of a furnaceroof construction of the invention taken longitudinally of the span ofthe arch;

FIGURE 2 is a sectional view of line 2-2 of FIG- URE l;

FIGURE 3 is a sectional View on line 3-3 of FIG- URE 2;

FGURE 4 is a sectional view showing a modfication of the interconnectionof the inverted T-beams and 1- beam of FIGURE 2;

FIGURE 5 is a sectional view on lineS- S of FIG- URE 4;

FIGURE 6 is a plan View of the sleeve and mounting braekets of thesleeve jack shown in FIGURE 2;

FIGURE 7 is a sectional View corresponding to a portion of FIGURE 2 butshowing a modification thereof;

FIGURE 8 is a sectional view on line 8-8 of FIG- URE 7; and

FIGURES 9aand 9b are a front view and side view, respectively, of abriclt clip employed in FIGURES 7 and 8.

Referring particularly to FIGURE 1, there is shown one embodment of thisinvention for a roof construction havingr a chord length ofapproximately 23 feet. This construction is provided with a transverselyspacedapart series of overhead, furnace support or binding, structuralmembers w rigidly secured to and supported from upright end members orbuckstays 11, which form a framework for the furnace refraetorysidewalls 12 and the fixed skewbacks 13. Additional support is providedto binding Channels by the two spacedapart,tranVersely-extending crosschannel members 15, which are rigidly secured to channels 1d.

While the skewback 13 illustrated here is of a steel constructionconfiguration, it may be made in any other conventional manner and ofother conventional materials, such as wedge-shaped refractory. In thisspecification and in the appended claims, the terms fixed skewbacks meanspaced-apart, opposed skewbacks having the distance between themmaintained substantially Constant at all times, which includes thenon-adjustable, rigidly placed type skewback conventional in the UnitedStates as well as the adjustable type skewback in common use in Europe,provided that in the latter case no adjustrneut is made afterconstruction of the roof has begun and for the entire life of the roof.

The refractory arch is conventionally constructed of somewhat key-shapedlonger rib-forming brick 2d and shorter valley-forming brick 2.1 (seeFIGURE 2) arranged in a series of alternating, arch-shaped rows of eachsize briek extending longitudinally of the span of the roof between thefiXed skewbacks 13. The bottom or hot faces of all the brick arearranged substantially lush along the are line of the roof span therebyforming the conventional rib and Valley arrangement on the top side orcold face of the refractory arch by Virtue of the longer rib-formingbriclr 20 extending upward beyond the valley-forming brick 21. It shouldbe understood, however, that the well-known drop Sections can be used iffurnace roof wear is unbalanced.

Adjacent bricl: rows are laid tightly together so that the hold-up andhold-down effect and the limited Vertical movement effect actingdirectly on the rib-forming brick 20 (as described below) will actindirectly on the Valley-forming briclr Zll through frictional contactand partial bonding that may occur between the two briek rows. Ifdesired, a conventional grout joint can be made, using well-knownrefractory cements, between the adjacent brick rows to assst in thisregard. However, it has been found that frietonal and bonding forcesbetween adjacent rows are insufiieient to indirectly control the contourof Valley-forming brick rows when five Valley rows are disposed betweenpairs of censecutively spaced rib rows. Thus, it is essential that notmore than four rows of valley-forming brick be used between pairs of.consecutively spaeed rib rows in this embodiment and partieularlydesirable results are obtained by using two or three Valley rows betweenrib rows.

In other words, at least every fifth brick row must have the unique dualeffect means of this invention acting directly on it, as will bedescribed below.

Referring now to FTGURES 1-5, longiudinal steel beam supports25 eXtendalong substantially the entire length of and on the cold face of eachrow of rib-forming bricl: 2d. Lengitudinal supports 25 have acomplementary arcuate configuration to the cold face of the rib rows andmay be made of one continuous length or in segments. Preferably,supports 25 consist of two or more segments of a length convenient tohandle on each brick row and have adjacent ends substantially near thecrown of the arch as indicated at 26 (see FIG- URES 1 and 3).Substantially every rib-forming brick 2d is interconneeted with thelongitudnal support 25 on its cold face, preferably by means ofstainless steel hangers or wires 27. In the embodiment shown in thedrawings, the upward extending portions of the ribforming bricks have ahole 28 drilled through them transversely of the rib brick row. Thewires 27 pass through holes 2.8 and the free ends of the wires 27 arewrapped over the support 25 and twisted together as indicated at 29. Ifdesired, the holes 28 need not be drilled all the way through the brick,but rather an aperture, notch or shallow hole can be drilled part wayinto each side of the upward extending portion of the rib-forming brick20 on the opposite sides adjacent the valley-forming brick 21. In thislatter case, stainless steel hangers can be made of rod, wrought orcast, formed into a tongs-like clip that can be fitted over the supports25 and its free ends inserted into the apertures, notches or shallowholes on opposite sides of each brick 20. While the foregoinginterconnection methods are deemed to be the best mode known at present,other suitable methods that will be apparent to those slrilled in theart can be used if dcsired.

Afranged over the longitudinal beams 25 and extending transversely ofthe roof span is a series of spacedapart, substantially parallel,transverse steel beam supports 3d. The transverse supports 30 aredesirable for economic reasons, explained m'ore fully below, but theycan be omitted if desired. Transverse supports 30) are held down againstand interconnected to longitudinal supports 25 at the points where theformer cross over the latter. means such as steel straps 31, whose freeends are welded to the side of the web of inverted, arch-shaped T-beams25, or by other suitable means.

seven transverse beams Citi substantially equally spaced over arefractory arch having a chord length of about 23 feet, more 'or lessthan this number can be used. As. a general rule it is found best to useat least one beam 30 for about every 4 feet of arch chord length. Also,where space between the transverse beams 3d nearest the crown of thearch and the furnace binding member 10 is extremely limited, a portionof the web of T-beams 25 can be cut out (in'dicated at 32 in FGURES 1and 3) at points where the transverse beams 30 nearest the crown of thearch cross over the T-beams 25. At these points 32. the beam 3h is helddown against the remaining web portion of the T-beams 25.

An additional, but optional, advantageous feature is to rigidly blockdown the extreme ends of the longitudinal beams 25 by means of steelbars 39 attached to the upper porti-on of skewbacks 13 (see FIGURE 1).

The limited amount of upward and downward movement, or breathing actionjof the refractory arch is provided by the Vertical movement controlmeans 41, 42, 43, 4M, 45, 46 and 47, which are shown as sleeve jacks inFIGURES 1 and 2. The sleeve jaeks comprise a tubular or pipe member 51slidably positioned within sleeve 52 and extending beyond both ends ofsleeve 52.. The lower end of pipe 51 is rigidly secured to transversebeam 3G) by means of boltv 53 and angle iron brackets 54, the latterbeing rigidly attached to beam 3d, such as by welding, bolting, etc. Thesleeve 52 is lrigidly secured to the furnace binding structural member1d by means of mounting brackets 5 (see FIGURES 2 and 6).. One leg ofeach mounting bracltet 55 is welded to sleeve 52 and the other leg isrigidly secured to member 10, such as by welding, bolting, etc. In orderto facilitate easier posi- This interconnection can be accomplished by`tioning of sleeve jacks 41 and 47 along the outermost portions of theroof span, sleeves 52. can be braclceted to steel structural plates 60(see FIGURE 1), the latter being :attached to binding channels andbuckstays 1.1.

A series of sleeve jacks are spaced along each transverse beam 30. Aspacing found suitable is about one jack for every three or four ribrows. Thus, the effect of each jack is distributed to severallongitudinal beams through the transverse beam 30. However, if it isdesired to omit the transverse beams 30, it will be necessary to usemore jacks spaced closer together, preferably jacks on each rib row,with the lower ends of pipes 51 suit'ably secured directly tolongitudinal beams 25.

The required limited movement allowance is provided by Vertical movementlimiting means, stop means or bolts 57 and 58 positioned through holesin pipe 51 above and below the sleeve 52. Thus, bolt 57 will limit thedownward traverse of pipe 51 when bolt 57 contacts the upper end iofsleeve 52. Likewise, bolt 58 will limit the upward traverse of pipe 51when bolt 58 contacts the lower end of sleeve 52.

In constructing the roof according to this invention, bolts 57 and 58are positioned appropriate predetermined distances X and Y, respectively(see FIGURE 2), for the particular refractory composition used. By wayof illustraton, an open hearth furnace roof was constructed according toFIGURES 1-6 using fused cast refractory brick having the followingapproximate composition in weight percent: 59% Mgo, 19% Cr203, 9% A1203,10% FeO, 2% Si02 and 1% CaO. The rib-forming brick Were 161/2 incheslong and the valley-forming brick were 131/2 inches long. The arch wasconstructed on a radius of curvature of about 21 feet with an expansionallowance on the hot face of about 07% per foot of arch length. The Xand Y allowance values determined for each sleeve jack with the roofinitially cold and found suitable in conventional open hearth practicewere as follows (in inches):

The higher Y values for some of the jacks refiect an 'allowance for theinitial expansion rise upon heating the furnace up to the normalstarting temperature for each heat of steel (i.e. about 2300 F.).

FIGURES 7-9 show a modified ernbodiment of the invention suitable foroonstructing a roof with all brick of the same length. Brick 61 are laidin arch-shaped rows as in the previous example according to conventionalpractice, but stainless steel brick clips 62 are inserted between brick61 at intervals along a pair of brick rows spaced from each other by onebrick row between the pair. Each brick clip 62 comprises a body portion63 that is disposed between brick 61, an upper extension 64 of the bodyportion 63 that extends upwardly from the cold face of briclc 61 and atab 65 joined to the upper extension 64 at a right angle.

Longitudinal support beams 66 extend along and on the oold face of thebrick row between the pair of rows containing the brick clips 62. Thesebeams 66 correspond to beams 25 in the previous example. Tabs 65 of theclips 62 are bent over to form a hanger-engaging relationship with beams66 (see FIGURE 7).V Transverse support beams 67, corresponding to beamsin the previous example, are arranged over longitudinal beams 66 inspaced-apart, substantially parallel relationship. Steel straps 68 holddown transverse beams 67 against the longitudinal beams 66, similar tothe interconnection formed by straps 31 above. The lower ends of sleevejack pipe members 69 (corresponding to pipes 51 above) are secured tobeams 67 by bolts '70, or other suitable means.

While sleeve jacks have been shown for providing the aisases 553breathing action to the refractory arch, it should be understood thatother suitable means can be employed, such as spring jacks known in theprior 'art and having appropriate limiting means to provide thenecessary limited movement allowance described above.

Hanger wires 27 and brick clips 62 are preferably made of, but notnecessarily restricted to, stainless steel grades commonly known in theprior art as American Iron and Steel Institute (A.I.S.l.) 300 and 400series compositions.

Roof constructions made in accordance with this invention, particularlythe embodiment of FGURES 1-6, have shown highly superior stability andlife in actual service performance. For example, in actual roofconstructions on open hearth furnaces that utilized the rnore recentpractice of tonnage oxygen lancing, three lasted for about 400 heatseach, one lasted for about 450 heats and another one lasted for over 500heats. The significance of the improved construction of this inventionis even notable in conventional open hearth practice not utilizingtonnage oxygen lancing where a roof was found to last about 500 heats.

lt should be understood that, although the roof construction of thisinvention was designed for and is essential to successful Contourcontrol of arches made of fused cast refractory, it can also be used forarches made of other types of refractory of high hot load strength if sodesirerl.

Although the present invention has been described with respect tospecific details of certain embodiments thereof, it is not intended thatsuch details be limitations upon the scope of the invention exceptinsofar as set forth in the following claims.

What is claimed is:

1. An arched furnace roof construction comprising:

(a) a series :of refractory brick rows extending in arch form betweenfixed skewbacks,

(b) an overhead furnace supporting structure fixed against Verticalmovement and arranged above said series of rows,

(c) Vertical movement control means having fixed upper and lower stopmeans thereon and being rigidly attached to said overhead supportingstructure and interconnected with at least every fifth brick row in saidseries, said Vertical movement control means adapted to allow only alimited amount of upward and downward movement of said brick rows, whilemaintaining substantially their original smooth contour, substantiallyequal to the rise and fall of said brick rows resulting solely fromthermal expansion and contraction of said brick caused by changes intheir temperature due to operational heating and cooling of the furnace.

2. An arched furnace roof construction according to claim 1 wherein thebrick is composed of fused cast refractory.

3. An arched furnace roof construction comprising:

(a) a series of fused cast refractory brick rows in abutting relationand extending in arch form between fixed slewbacks,

(b) a series of spaced-apart longitudinal support means extendinglongitudinally of the span of the roof along and on the cold face ofsaid brick rows, and each longitudinal support means interconnected withat least every fifth brick row,

(c) an overhead furnace supporting structure fixed against Verticalmovement and arranged above said series of longitudinal support means,

(d) Vertical movement control means having fixed upper and lower stopmeans thereon and being rigidly attached to said overhead supportingstructure and interconnected with said longitudinal support means, saidVertical movement control means adapted to allow only a limited amountof upward and down- Ward movement of said brick rows, while maintainingsubstantially their original smooth Contour, substantially equal to therise and fall of said bricl: rows resulting solely from thermalexpansion and contraction of said brick caused by changes in theirtemperature due to operational heating and cooling of the furnace.

19 (f) hangers engaging the apertures in said rib-forming brick andvinterconnecting said longitudinal steel beams and said rib-formingbrick, (g) a series of substantially parallel transverse steel 4. Anarched furnace roof construction comprising: beams arranged over saidlongitudinal steel bearns (a) two sizes of fused cast refractory brickconsisting and spaced longitudinally of and extending transof longerrib-forming brick extending upward beversely of the span of the roof,yond shorter valley-forming brick on the cold face (lz) strapsinterconnecting said transverse steel beams of said roof, and saidlongitudinal steel beams at points where (b) said brick of each sizearranged in a series of rows said transverse steel beams cross over saidlonghaving the arch configuration of and extending longtudinal steelbeams, tudinally of the span of the roof between fixed skew- (i) anOVel'llead furnace binding Structure fiXed against backs, Verticalmovement and arranged above said trans- (c) said rows of rib-formingbrick spaced transversely verse steel beams,

.of the span of the roof, (j) a plurality of vertically variable jacksarranged (d) One to four of said rows of valley-forming brck over andspaced along said transverse steel bearns, being disposed between and inabutting relation to the lOWer endS `Of Said nCkS figidiy Httaeiled tOSaid each pair of consecutively spaced rows of rib-forming tran-SVefSeSteel beaniS and the Upper endS Of Said brick, jacks rigidly attached tosaid furnace binding struc- (e) longitudinal support means extendinglongitudinaltnie,

ly of the span of the roof along and .on the cold face (k) fiXed Upperand lOWef StOP InennS On Said jackS of rib-forming brick rows, saidl-ongitudinal support adapted tO allOW Only a limited amount Of UPWaFdmeans having a complementary arouate oonfiguraand downward movement ofsaid brick rows, while tion to the cold face of Said rib-forming briokrows, maintaining substantially their original smooth con- IneanSntereonnecting said longitudinal support tour, substantially equal tothe rise and fall of said means and said rib-forming briok rows, brickrows resulting solely from thermal expansion g) an overhead furnacesupporting structure fixed and COntfCtiOn Of Said briek caused byChanges in against Vertical movement and arranged above said theirtemperature due tO `C'Pefntinnli henting and longitudinal support means,Cooling of the furnace.

(h) Vertical movoment control means having fixed up- 7. An archedfurnace roof construction according to per and lower stop means thereonand being rigidiy claim 6 having two to three rows of valley-forrningbrick attaohed to said overhead Supporting Structure and disposedbetween and in abutting relation to each pair of interconnected withsaid longitudinal support means, COnSeCi-iiively Spad roWS Ofrib'fOrIning brick- Said Vertical movement eontml means adapted to 8. Anarched furnace roof construction comprising: allow Only a limited amountof upward and down- (L1.) a series of fused cast refractory brick rowsin abut- Ward movernent of said brick rows, while maintain- 111grelation and exiending in M011 fOIm between fiXed ing substantiallytheir original smooth Contour, sub- SkeWbaCkS,

stantially equal to the rise and fall of said brick rows (b)longiiudinal Steel beanlS eXtending lngitndnally resulting solely fromthermal expansion and contracof the sPan Of the 1'00f alOng and On theCOld face Of tion of said briok caused by changes in their tem- ,w everyfourth brick row, said longitudinal steel beams perature due toOperationai heating and Cooling of having acomplementary arcuateconfiguration to said the furnace cold face of said brick rows,

5, An arched furnace rnof Construction accnrding to (c) plates disposedtransversely between at least every daim 4 including: fifth brick jointin the briclr rows adjacent said every (a) a series 'of substantiallyparallel transverse support fourth bfick fW Said Plates having aP01'ti0n extendmeans arranged over said longitudinal support means m5upwmfdiy beyond the Cold face Of Said bl'iel end and spacedlongitudinally of and extending transsaid portion interconnecting saidlongitudinal steel versely of the span of the roof, said transverse supi'beams With Said Piates, port means rigidly attached to said Verticalmove- (d) a series of substantially parallel transverse steel mentcontrol means, and 'beams arranged over said longitudinal steel beams(b) means interconnecting said transverse support and Spadiongiiudinally Of and eXtending fnnS- means and said longitudinalsupport means. Versely of 'the 'SPan Of the 1`00f,

6, An arched furnace rnof Construction comprisng: (a) strapsinterconnecting said transverse steel beams (a) two sizes of fused castrefractory brick consisting anfl Said longiiudinal Steel beanls ntPnintS Where of longm. l.ib forming bn-ck having a porton eX saidtransverse steel beams cross over said longituditending upwardly beyondshorter valley-forming mi Steel beamsz brick on the cold face of theroof, Said upwardiy (f) an overhead furnace binding structure fixedagainst eXtendng POTtiOn 'of Said rb-forming brick having Verticalmovernent and arranged above said transan aperture in each of theopposite sides of the rib- Vefs Steel beainS, forming brick adjacent thevalley-forming brick, (g) a Piumiiiy Of VefiiClllY Vfinble J'ReiSal'rf'lnged (b) said briclr 'of each size arranged in a series of rowsOver and Spad along Said tI'anSVefSe Steel beniS, having the ;ii-ohConfiguration of and extending 10ngi the lower ends of said jacksrigidly attached to said tudinally of the span of :the roof betweenfixed skew- 'ansvefsc Steel beams and the Upper endS Of Said backs,jacks rigidly attached to said furnace binding struc- (c) said rows ofrib-forming brick spaced transversely Gr tnfe,

of the Span Of the ronf, d (h) fixed upper and lower stop means on saidjacks (d) one to four of Said rows of vaueyionm-ng brick adapted toallow only a limited amount of upward being disposed between and inabutting relation to and. dqwfiward movment 'of Said brick rows, Whileeach pair of consecutively spaced rows of rib-forming mamtammgSllbstanauy their Original Smooth Con' brick, tour, substantially equalto the rise and fall of said (e) longimdinal Steel beams extendinglongitudnany brick rows resultmg s'olely. from thermal expansion of thespan of said roof along and .on the cold face cntracon of Said bnckcaued by Chimges in of rib-forming brick rows, said longitudinal steelcogln enplraure due to 'operatmnal heatmg and 'beams having acomplementary arcuate configuration g O e uma' to the cold face of saidrib-forming brick rows,

(References on following page) i 11 12 References Ced by 1116: Examiner3,015,288 1/62 Hosbein et al 110-99 UNITED STATES PATENTS 3,1G4,631 9/63Copeland 110-99 1,130,345 3/15 Stevens 110 99 FOREIGN PATENTS 1,317,4609/ 19 Stevens. 5 213,428 2/61 Austria. 2,222,978 11/40 Kiren 110-99938,265 1/56 Germany. 2,659,326 11/53 Hong 11() 99 2,7g1,()06 2/57 Heuer110 99 IAMES W. WESTHAVER, Primary Exammer. 3,005,424 10/61 Heller110-99 PERCY L. PATRICK, FREDERICK KET'IERER,

3,013,510 12/61 Parker ..-110-99 10 Examiners.

1. AN ARCHED FURNACE ROOF CONSTRUCTION COMPRISING (A) A SERIES OFREFRACTORY BRICK ROWS EXTENDING IN ARCH FROM BETWEEN FIXED SKEWBACKS,(B) AN OVER HEAD FURNACE SUPPORTING STRUCTURE FIXED AGAINST VERTICALMOVEMENT AND ARRANGED ABOVE SAID SERIES OF ROWS, (C) VERTICAL MOVEMENTCONTROL MEANS HAVING FIXED UPPER AND LOWER STOP MEANS THEREON AND BEINGRIGIDLY ATTACHED TO SAID OVERHEAD SUPPORTING STRUCTURE ANDINTERCONNECTED WITH AT LEAST EVERY FIFTH BRICK ROW IN SAID SERIES, SAIDVERTICAL MOVEMENT CONTROL MEANS ADAPTED TO ALLOW ONLY A LIMITED AMOUNTOF UPWARD AND DOWNWARD MOVEMENT OF SAID BRICK ROWS, WHILE MAINTAININGSUBSTANTIALLY THEIR ORIGINAL SMOOTH CONTOUR, SUBSTANTIALLY EQUAL TO THERISE AND FALL OF SAID BRICK ROWS RESULTING SOLELY FROM THERMAL EXPANSIONAND CONTRACTION OF BRICK CAUSED BY CHANGES IN THEIR TEMPERATURE DUE TOOPERATIONAL HEATING AND COOLING OF THE FURNACE.